diff mbox

tpm: remove redundant code from self-test functions

Message ID 1459344045-21602-1-git-send-email-jarkko.sakkinen@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jarkko Sakkinen March 30, 2016, 1:20 p.m. UTC 
Self-test functions construct PCR read calls by ad hoc, which is only a
waste space. Use instead tpm_pcr_read_dev (renamed as tpm1_pcr_read() by
this commit) in tpm_do_selftest and tpm2_pcr_read() in
tpm2_do_selftest() functions in order to remove the duplicate code.

Patch can be tested easily tested by running the a kernel with this
patch compiled in since self-test is done when the a device driver
initializes.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 drivers/char/tpm/tpm-interface.c | 14 +++++---------
 drivers/char/tpm/tpm-sysfs.c     |  2 +-
 drivers/char/tpm/tpm.h           |  2 +-
 drivers/char/tpm/tpm2-cmd.c      | 14 ++------------
 4 files changed, 9 insertions(+), 23 deletions(-)

Comments

Jarkko Sakkinen March 30, 2016, 1:25 p.m. UTC | #1 
On Wed, Mar 30, 2016 at 04:20:45PM +0300, Jarkko Sakkinen wrote:
> Self-test functions construct PCR read calls by ad hoc, which is only a
> waste space. Use instead tpm_pcr_read_dev (renamed as tpm1_pcr_read() by
> this commit) in tpm_do_selftest and tpm2_pcr_read() in
> tpm2_do_selftest() functions in order to remove the duplicate code.
> 
> Patch can be tested easily tested by running the a kernel with this
> patch compiled in since self-test is done when the a device driver
> initializes.

This is now fixed version (I forgot to squash one fixup to the previous
version). This could use peer test preferably with a FIFO device. It is
easy as one only needs to load the driver and see that there are no
errors in dmesg from self-additions. As an additional measure on a TPM
1.x device outputting 'pcrs' file could be a good idea.

/Jarkko

> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  drivers/char/tpm/tpm-interface.c | 14 +++++---------
>  drivers/char/tpm/tpm-sysfs.c     |  2 +-
>  drivers/char/tpm/tpm.h           |  2 +-
>  drivers/char/tpm/tpm2-cmd.c      | 14 ++------------
>  4 files changed, 9 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 5397b64..0c8140f 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -1,6 +1,6 @@
>  /*
>   * Copyright (C) 2004 IBM Corporation
> - * Copyright (C) 2014 Intel Corporation
> + * Copyright (C) 2014, 2016 Intel Corporation
>   *
>   * Authors:
>   * Leendert van Doorn <leendert@watson.ibm.com>
> @@ -666,7 +666,7 @@ static struct tpm_input_header pcrread_header = {
>  	.ordinal = TPM_ORDINAL_PCRREAD
>  };
>  
> -int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
> +int tpm1_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
>  {
>  	int rc;
>  	struct tpm_cmd_t cmd;
> @@ -676,7 +676,7 @@ int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
>  	rc = tpm_transmit_cmd(chip, &cmd, READ_PCR_RESULT_SIZE,
>  			      "attempting to read a pcr value");
>  
> -	if (rc == 0)
> +	if (rc == 0 && res_buf)
>  		memcpy(res_buf, cmd.params.pcrread_out.pcr_result,
>  		       TPM_DIGEST_SIZE);
>  	return rc;
> @@ -728,7 +728,7 @@ int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf)
>  	if (chip->flags & TPM_CHIP_FLAG_TPM2)
>  		rc = tpm2_pcr_read(chip, pcr_idx, res_buf);
>  	else
> -		rc = tpm_pcr_read_dev(chip, pcr_idx, res_buf);
> +		rc = tpm1_pcr_read(chip, pcr_idx, res_buf);
>  	tpm_put_ops(chip);
>  	return rc;
>  }
> @@ -793,7 +793,6 @@ int tpm_do_selftest(struct tpm_chip *chip)
>  	unsigned int loops;
>  	unsigned int delay_msec = 100;
>  	unsigned long duration;
> -	struct tpm_cmd_t cmd;
>  
>  	duration = tpm_calc_ordinal_duration(chip, TPM_ORD_CONTINUE_SELFTEST);
>  
> @@ -808,9 +807,7 @@ int tpm_do_selftest(struct tpm_chip *chip)
>  
>  	do {
>  		/* Attempt to read a PCR value */
> -		cmd.header.in = pcrread_header;
> -		cmd.params.pcrread_in.pcr_idx = cpu_to_be32(0);
> -		rc = tpm_transmit(chip, (u8 *) &cmd, READ_PCR_RESULT_SIZE);
> +		rc = tpm1_pcr_read(chip, 0, NULL);
>  		/* Some buggy TPMs will not respond to tpm_tis_ready() for
>  		 * around 300ms while the self test is ongoing, keep trying
>  		 * until the self test duration expires. */
> @@ -825,7 +822,6 @@ int tpm_do_selftest(struct tpm_chip *chip)
>  		if (rc < TPM_HEADER_SIZE)
>  			return -EFAULT;
>  
> -		rc = be32_to_cpu(cmd.header.out.return_code);
>  		if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
>  			dev_info(&chip->dev,
>  				 "TPM is disabled/deactivated (0x%X)\n", rc);
> diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
> index 34e7fc7..48e30bd 100644
> --- a/drivers/char/tpm/tpm-sysfs.c
> +++ b/drivers/char/tpm/tpm-sysfs.c
> @@ -101,7 +101,7 @@ static ssize_t pcrs_show(struct device *dev, struct device_attribute *attr,
>  
>  	num_pcrs = be32_to_cpu(cap.num_pcrs);
>  	for (i = 0; i < num_pcrs; i++) {
> -		rc = tpm_pcr_read_dev(chip, i, digest);
> +		rc = tpm1_pcr_read(chip, i, digest);
>  		if (rc)
>  			break;
>  		str += sprintf(str, "PCR-%02d: ", i);
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index cd780c7..89740db 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -511,7 +511,7 @@ extern void tpm_chip_unregister(struct tpm_chip *chip);
>  int tpm_sysfs_add_device(struct tpm_chip *chip);
>  void tpm_sysfs_del_device(struct tpm_chip *chip);
>  
> -int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
> +int tpm1_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
>  
>  #ifdef CONFIG_ACPI
>  extern void tpm_add_ppi(struct tpm_chip *chip);
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 5fc0e7c..afe8d47 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -284,7 +284,7 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
>  
>  	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd),
>  			      "attempting to read a pcr value");
> -	if (rc == 0) {
> +	if (rc == 0 && res_buf) {
>  		buf = cmd.params.pcrread_out.digest;
>  		memcpy(res_buf, buf, TPM_DIGEST_SIZE);
>  	}
> @@ -861,7 +861,6 @@ int tpm2_do_selftest(struct tpm_chip *chip)
>  	unsigned int loops;
>  	unsigned int delay_msec = 100;
>  	unsigned long duration;
> -	struct tpm2_cmd cmd;
>  	int i;
>  
>  	duration = tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST);
> @@ -874,19 +873,10 @@ int tpm2_do_selftest(struct tpm_chip *chip)
>  
>  	for (i = 0; i < loops; i++) {
>  		/* Attempt to read a PCR value */
> -		cmd.header.in = tpm2_pcrread_header;
> -		cmd.params.pcrread_in.pcr_selects_cnt = cpu_to_be32(1);
> -		cmd.params.pcrread_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
> -		cmd.params.pcrread_in.pcr_select_size = TPM2_PCR_SELECT_MIN;
> -		cmd.params.pcrread_in.pcr_select[0] = 0x01;
> -		cmd.params.pcrread_in.pcr_select[1] = 0x00;
> -		cmd.params.pcrread_in.pcr_select[2] = 0x00;
> -
> -		rc = tpm_transmit_cmd(chip, (u8 *) &cmd, sizeof(cmd), NULL);
> +		rc = tpm2_pcr_read(chip, 0, NULL);
>  		if (rc < 0)
>  			break;
>  
> -		rc = be32_to_cpu(cmd.header.out.return_code);
>  		if (rc != TPM2_RC_TESTING)
>  			break;
>  
> -- 
> 1.9.1
> 

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Jason Gunthorpe March 31, 2016, 5:46 a.m. UTC | #2 
On Wed, Mar 30, 2016 at 04:20:45PM +0300, Jarkko Sakkinen wrote:
  
> -		rc = be32_to_cpu(cmd.header.out.return_code);
>  		if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {

This line is the entire reason it is open coded, I see it being
removed, but I don't see how the functionality is maintained?

Jason

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Jarkko Sakkinen March 31, 2016, 6:37 a.m. UTC | #3 
On Wed, Mar 30, 2016 at 11:46:23PM -0600, Jason Gunthorpe wrote:
> On Wed, Mar 30, 2016 at 04:20:45PM +0300, Jarkko Sakkinen wrote:
>   
> > -		rc = be32_to_cpu(cmd.header.out.return_code);
> >  		if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
> 
> This line is the entire reason it is open coded, I see it being
> removed, but I don't see how the functionality is maintained?

When tpm_trance_cmd() returns a positive number it is the TPM error code
that it returns. tpm_pcr_read() does pass through whatever
tpm_trace_cmd() returns so the above condition should still work as
expected.

> Jason

/Jarkko

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Jason Gunthorpe April 2, 2016, 3:16 a.m. UTC | #4 
On Thu, Mar 31, 2016 at 09:37:56AM +0300, Jarkko Sakkinen wrote:
> On Wed, Mar 30, 2016 at 11:46:23PM -0600, Jason Gunthorpe wrote:
> > On Wed, Mar 30, 2016 at 04:20:45PM +0300, Jarkko Sakkinen wrote:
> >   
> > > -		rc = be32_to_cpu(cmd.header.out.return_code);
> > >  		if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
> > 
> > This line is the entire reason it is open coded, I see it being
> > removed, but I don't see how the functionality is maintained?
> 
> When tpm_trance_cmd() returns a positive number it is the TPM error code
> that it returns. tpm_pcr_read() does pass through whatever
> tpm_trace_cmd() returns so the above condition should still work as
> expected.

Okay, everything looks fine to me

Jason

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Jarkko Sakkinen April 5, 2016, 9:42 a.m. UTC | #5 
On Fri, Apr 01, 2016 at 09:16:15PM -0600, Jason Gunthorpe wrote:
> On Thu, Mar 31, 2016 at 09:37:56AM +0300, Jarkko Sakkinen wrote:
> > On Wed, Mar 30, 2016 at 11:46:23PM -0600, Jason Gunthorpe wrote:
> > > On Wed, Mar 30, 2016 at 04:20:45PM +0300, Jarkko Sakkinen wrote:
> > >   
> > > > -		rc = be32_to_cpu(cmd.header.out.return_code);
> > > >  		if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
> > > 
> > > This line is the entire reason it is open coded, I see it being
> > > removed, but I don't see how the functionality is maintained?
> > 
> > When tpm_trance_cmd() returns a positive number it is the TPM error code
> > that it returns. tpm_pcr_read() does pass through whatever
> > tpm_trace_cmd() returns so the above condition should still work as
> > expected.
> 
> Okay, everything looks fine to me

I applied this to http://git.infradead.org/users/jjs/linux-tpmdd.git in
order to get exposure (tested-by's are always welcome).

> Jason

/Jarkko

------------------------------------------------------------------------------
Christophe Ricard April 6, 2016, 2:03 p.m. UTC | #6 
Hi Jarkko,

I think there is a bug in the current version of this patch.
tpm1_pcr_read returns TPM status code (>= 0)

In tpm_do_selftest, after tpm1_pcr_read, rc is compared with
TPM_HEADER_SIZE.

In short:
"if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {" is never
reached because TPM_ERR_DISABLED(0x7) and TPM_ERR_DEACTIVATED(0x6) are <
TPM_HEADER size.
TPM_HEADER_SIZE beeing already checked in tpm_transmit_cmd, i think a
reasonable fix will be to remove:
if (rc < TPM_HEADER_SIZE)
       return -EFAULT;

in tpm_do_self_test.

Can you merge this fix into the current patch or do you want me to send it
to you ?

Best Regards
Christophe


2016-04-05 11:42 GMT+02:00 Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
:

> On Fri, Apr 01, 2016 at 09:16:15PM -0600, Jason Gunthorpe wrote:
> > On Thu, Mar 31, 2016 at 09:37:56AM +0300, Jarkko Sakkinen wrote:
> > > On Wed, Mar 30, 2016 at 11:46:23PM -0600, Jason Gunthorpe wrote:
> > > > On Wed, Mar 30, 2016 at 04:20:45PM +0300, Jarkko Sakkinen wrote:
> > > >
> > > > > -               rc = be32_to_cpu(cmd.header.out.return_code);
> > > > >                 if (rc == TPM_ERR_DISABLED || rc ==
> TPM_ERR_DEACTIVATED) {
> > > >
> > > > This line is the entire reason it is open coded, I see it being
> > > > removed, but I don't see how the functionality is maintained?
> > >
> > > When tpm_trance_cmd() returns a positive number it is the TPM error
> code
> > > that it returns. tpm_pcr_read() does pass through whatever
> > > tpm_trace_cmd() returns so the above condition should still work as
> > > expected.
> >
> > Okay, everything looks fine to me
>
> I applied this to http://git.infradead.org/users/jjs/linux-tpmdd.git in
> order to get exposure (tested-by's are always welcome).
>
> > Jason
>
> /Jarkko
>
------------------------------------------------------------------------------
Jarkko Sakkinen April 7, 2016, 11:30 a.m. UTC | #7 
On Wed, Apr 06, 2016 at 04:03:52PM +0200, Christophe Ricard wrote:
>    Hi Jarkko,
> 
>    I think there is a bug in the current version of this patch.
>    tpm1_pcr_read returns TPM status code (>= 0)
> 
>    In tpm_do_selftest, after tpm1_pcr_read, rc is compared with
>    TPM_HEADER_SIZE.
> 
>    In short:
>    "if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {" is never
>    reached because TPM_ERR_DISABLED(0x7) and TPM_ERR_DEACTIVATED(0x6) are <
>    TPM_HEADER size.
>    TPM_HEADER_SIZE beeing already checked in tpm_transmit_cmd, i think a
>    reasonable fix will be to remove:
>    if (rc < TPM_HEADER_SIZE)
>           return -EFAULT;
> 
>    in tpm_do_self_test.
> 
>    Can you merge this fix into the current patch or do you want me to send it
>    to you ?

This is my bad and thanks for catching this. I tested the patch but for
some reason the patch that I sent to LKML does not have this check
removed. The check can be safely removed because the same check is done
internally by tpm_transmit().

For now I removed the patch from my master branch since there is a crash
that I'm debugging and this is low priority change. I'll include this
change among couple of other patches to a patches to a patch set that
unifies all parts to call tpm_transmit_cmd() later on.

Thanks again for spotting this!

/Jarkko

>    Best Regards
>    Christophe
>    2016-04-05 11:42 GMT+02:00 Jarkko Sakkinen
>    <jarkko.sakkinen@linux.intel.com>:
> 
>      On Fri, Apr 01, 2016 at 09:16:15PM -0600, Jason Gunthorpe wrote:
>      > On Thu, Mar 31, 2016 at 09:37:56AM +0300, Jarkko Sakkinen wrote:
>      > > On Wed, Mar 30, 2016 at 11:46:23PM -0600, Jason Gunthorpe wrote:
>      > > > On Wed, Mar 30, 2016 at 04:20:45PM +0300, Jarkko Sakkinen wrote:
>      > > >
>      > > > > -               rc =
>      be32_to_cpu(cmd.header.out.return_code);
>      > > > >                 if (rc == TPM_ERR_DISABLED || rc ==
>      TPM_ERR_DEACTIVATED) {
>      > > >
>      > > > This line is the entire reason it is open coded, I see it being
>      > > > removed, but I don't see how the functionality is maintained?
>      > >
>      > > When tpm_trance_cmd() returns a positive number it is the TPM error
>      code
>      > > that it returns. tpm_pcr_read() does pass through whatever
>      > > tpm_trace_cmd() returns so the above condition should still work as
>      > > expected.
>      >
>      > Okay, everything looks fine to me
> 
>      I applied this to http://git.infradead.org/users/jjs/linux-tpmdd.git in
>      order to get exposure (tested-by's are always welcome).
> 
>      > Jason
>      /Jarkko

------------------------------------------------------------------------------
diff mbox

Patch

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 5397b64..0c8140f 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1,6 +1,6 @@ 
 /*
  * Copyright (C) 2004 IBM Corporation
- * Copyright (C) 2014 Intel Corporation
+ * Copyright (C) 2014, 2016 Intel Corporation
  *
  * Authors:
  * Leendert van Doorn <leendert@watson.ibm.com>
@@ -666,7 +666,7 @@  static struct tpm_input_header pcrread_header = {
 	.ordinal = TPM_ORDINAL_PCRREAD
 };
 
-int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
+int tpm1_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
 {
 	int rc;
 	struct tpm_cmd_t cmd;
@@ -676,7 +676,7 @@  int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
 	rc = tpm_transmit_cmd(chip, &cmd, READ_PCR_RESULT_SIZE,
 			      "attempting to read a pcr value");
 
-	if (rc == 0)
+	if (rc == 0 && res_buf)
 		memcpy(res_buf, cmd.params.pcrread_out.pcr_result,
 		       TPM_DIGEST_SIZE);
 	return rc;
@@ -728,7 +728,7 @@  int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf)
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		rc = tpm2_pcr_read(chip, pcr_idx, res_buf);
 	else
-		rc = tpm_pcr_read_dev(chip, pcr_idx, res_buf);
+		rc = tpm1_pcr_read(chip, pcr_idx, res_buf);
 	tpm_put_ops(chip);
 	return rc;
 }
@@ -793,7 +793,6 @@  int tpm_do_selftest(struct tpm_chip *chip)
 	unsigned int loops;
 	unsigned int delay_msec = 100;
 	unsigned long duration;
-	struct tpm_cmd_t cmd;
 
 	duration = tpm_calc_ordinal_duration(chip, TPM_ORD_CONTINUE_SELFTEST);
 
@@ -808,9 +807,7 @@  int tpm_do_selftest(struct tpm_chip *chip)
 
 	do {
 		/* Attempt to read a PCR value */
-		cmd.header.in = pcrread_header;
-		cmd.params.pcrread_in.pcr_idx = cpu_to_be32(0);
-		rc = tpm_transmit(chip, (u8 *) &cmd, READ_PCR_RESULT_SIZE);
+		rc = tpm1_pcr_read(chip, 0, NULL);
 		/* Some buggy TPMs will not respond to tpm_tis_ready() for
 		 * around 300ms while the self test is ongoing, keep trying
 		 * until the self test duration expires. */
@@ -825,7 +822,6 @@  int tpm_do_selftest(struct tpm_chip *chip)
 		if (rc < TPM_HEADER_SIZE)
 			return -EFAULT;
 
-		rc = be32_to_cpu(cmd.header.out.return_code);
 		if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
 			dev_info(&chip->dev,
 				 "TPM is disabled/deactivated (0x%X)\n", rc);
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 34e7fc7..48e30bd 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -101,7 +101,7 @@  static ssize_t pcrs_show(struct device *dev, struct device_attribute *attr,
 
 	num_pcrs = be32_to_cpu(cap.num_pcrs);
 	for (i = 0; i < num_pcrs; i++) {
-		rc = tpm_pcr_read_dev(chip, i, digest);
+		rc = tpm1_pcr_read(chip, i, digest);
 		if (rc)
 			break;
 		str += sprintf(str, "PCR-%02d: ", i);
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index cd780c7..89740db 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -511,7 +511,7 @@  extern void tpm_chip_unregister(struct tpm_chip *chip);
 int tpm_sysfs_add_device(struct tpm_chip *chip);
 void tpm_sysfs_del_device(struct tpm_chip *chip);
 
-int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
+int tpm1_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
 
 #ifdef CONFIG_ACPI
 extern void tpm_add_ppi(struct tpm_chip *chip);
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 5fc0e7c..afe8d47 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -284,7 +284,7 @@  int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
 
 	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd),
 			      "attempting to read a pcr value");
-	if (rc == 0) {
+	if (rc == 0 && res_buf) {
 		buf = cmd.params.pcrread_out.digest;
 		memcpy(res_buf, buf, TPM_DIGEST_SIZE);
 	}
@@ -861,7 +861,6 @@  int tpm2_do_selftest(struct tpm_chip *chip)
 	unsigned int loops;
 	unsigned int delay_msec = 100;
 	unsigned long duration;
-	struct tpm2_cmd cmd;
 	int i;
 
 	duration = tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST);
@@ -874,19 +873,10 @@  int tpm2_do_selftest(struct tpm_chip *chip)
 
 	for (i = 0; i < loops; i++) {
 		/* Attempt to read a PCR value */
-		cmd.header.in = tpm2_pcrread_header;
-		cmd.params.pcrread_in.pcr_selects_cnt = cpu_to_be32(1);
-		cmd.params.pcrread_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
-		cmd.params.pcrread_in.pcr_select_size = TPM2_PCR_SELECT_MIN;
-		cmd.params.pcrread_in.pcr_select[0] = 0x01;
-		cmd.params.pcrread_in.pcr_select[1] = 0x00;
-		cmd.params.pcrread_in.pcr_select[2] = 0x00;
-
-		rc = tpm_transmit_cmd(chip, (u8 *) &cmd, sizeof(cmd), NULL);
+		rc = tpm2_pcr_read(chip, 0, NULL);
 		if (rc < 0)
 			break;
 
-		rc = be32_to_cpu(cmd.header.out.return_code);
 		if (rc != TPM2_RC_TESTING)
 			break;